1. Field of the Invention
The invention relates to a bioreactor vessel having an optical foam sensor which comprises a foam contact surface for contacting the foam to be detected.
2. Description of the Related Art
More particularly, the invention relates to bioreactor vessels having flexible outer walls that are especially suitable for use as disposable bioreactor vessels.
EP 1 950 281 B1 discloses bioreactor vessels having optical foam sensors. However, the bioreactor vessels disclosed in the aforementioned document do not have flexible outer walls. Specific details about the optical foam sensors are not disclosed in the aforementioned document. However, what is disclosed is that the foam sensors have a contact surface which is composed of dirt- and water-repellent material and at which foam produced in the course of a reaction taking place in the bioreactor container comes into contact and can be detected. In many bioreactions, more particularly in cell cultures and fermentations, foam development is a virtually unavoidable, but undesired, process. In particular, there is the risk of foam blocking off-gas filters, and this can lead to a rise in pressure in the reactor. Especially in the case of bioreactor vessels having flexible outer walls, this can lead to leakages, which can only be prevented by automatically switching off the gas supply. However, this constitutes an adverse influence on the process in the reactor. It is possible to counter the phenomenon of foam development by the metered addition of surface-active substances, known as antifoaming agents. However, they can have an adverse effect on the possibly sensitive biological process in the reactor, and so they must be used very sparingly. This can only be achieved when the actual and current demand for antifoaming agents, i.e. the actual and current status of foam development, can be captured reliably and without a large time lag. Such capture must be achieved using reliable and fast foam detectors, which can be connected to controllable metering pumps for the antifoaming agents via appropriate control electronics.
The aforementioned document addresses the problem of foam permanently accumulating on the contact surface, so that the detector is not able to recognize foam regression brought about by metered-in antifoaming agents. This would lead to overmetering of the antifoaming agents with the abovementioned disadvantages. The corrective action proposed by the aforementioned document is for an interior space of the foam detector to be made so large that no capillary effect can develop which could retain the foam in the detector space. This is associated with a disadvantageous structural enlargement.
DE 10 2006 044 076 A1 discloses a photocatalytically active coating for surfaces of buildings, vehicles, appliances, equipment, pathways and the like which consists of titanium dioxide nanoparticles in the anatase configuration and is activated by the UV components of daylight.
It is an object of the present invention to provide a bioreactor vessel, more particularly a bioreactor vessel having flexible outer walls, which has improved foam sensor technology.